I need some Help. One cold morning I came out and my battery was dead, a 4 year old battery so I replaced it. I checked the voltage while running because the red battery light would come on and go out. I got 12.4 volts so I replaced the alternator. I drove the car 3 days in a row and all was good then I let the car sit for 2 days and I came out to a dead battery. I thought maybe the battery was a dude so I drove the car to Advance Auto where I bought the battery. They tested the battery and confirmed it dead and gave me a replacement. They hooked up a Test device to the battery, it had 3 leads one to each side of the battery and a third that went around the negative cable sort of like a round clamp that did not actually clamp on the cable. He told me there was no drain on the battery while the car was off and that I should be OK. I went out today to a dead battery. I had previously checked all the fuses under the hood and inside the car under the dash where the driver sits and found no voltage going thru the fuses. I'm assuming the only two thing that could be draining the battery would be the alternator and the starter. How do I go about checking these?

 

when I disconnet the negative battery cable and put a volt meter in between I get a reading of -12 volts. I don't have an amp meter. When I disconnect the lead on the positive cable going to the alternator the meter just jumps between Volts and mili volts no steady numbers.

 

get an ammeter. Youre looking for current, not voltage.

lthough according to autoshop there is no drain.
2 days is a pretty quick drain.

The alternator charges the batt, the starter only draws when cranking.

Unless you have a short to ground.

The fluctuating reading...? Like a blinking light, or some electrical thing trying to draw startup current but failing, repeatedly.

 

the wandering voltage reading could just be the meter floating, if the voltage value remains very low, though it is curious you have steady 12v at the neg cable but not the pos. do you have a large audio amp in the car? if so, unplug the power when you park for several days for a check. the starter is not likely to be the problem unless it has dirt and corrosion between terminals. just for grins, have you checked your brake light switch? it can be intermittent and irritating. if you have any after market stuff, disconnect it and see what happens. also, by your name, can i assume you go offroad in this vehicle? i ask because intermittents like this can be caused by dirt and moisture. if the dirt is there, all it may take is some rain to complete the circuit. does this fit a pattern? if the car is old, dirt abounds in switches and on contacts. if the problem is frequent enough to make this not extremely irritating and the car can sit two or three days, pull a group of fuses and see what happens. then another group 'till done. if the battery dies, pull one fuse from the suspect group every time you can. this could take a while. but first, once again leaving it parked for a few days, pull all the relays and check the sockets and bottom of relays for dirt or corrosion. if so, clean them and spray the sockets with no residue contact cleaner. if any or this works, great. if not get a charger with a twenty amp setting so you're not stranded. would take twenty or thirty minutes to charge enough to start. or a jump start power supply for many more dollars. good luck!